I want to make the DIY hop randall from a plastic, inline, water filter housing. The acidity of the beer supposedly makes it unsafe to use with copper, brass, galvanized, or plastic. It seems that a lot of people have them with no problems though. Do I just worry about nothing?

With the exception of galvanized, the other materials are COMMONLY used by homebrewers. Peruse the DIY brew sculptures and you will see a lot of copper and brass. Fermenting in plastic buckets or plastic carboys is standard as well.

But it is food safe plastic and the copper/brass is used before fermentation so the acidity isn't a factor yet, right? I hear that those metals are very bad when used with acidic foods. Maybe it's not as bad as I'm reading online.

But it is food safe plastic and the copper/brass is used before fermentation so the acidity isn't a factor yet, right? I hear that those metals are very bad when used with acidic foods. Maybe it's not as bad as I'm reading online.

No, the wort is just as acidic before fermentation as after. Ethanol has a PH very near 7.0 which is neutral. Perhaps you should start reading more things here

There is a link to a blog post around here where someone is claiming Bud Light will kill because they use GMO grains and what not, I think a few million Bud Light drinkers still living prove that one wrong!

It's been my experience that when it comes to what people "believe", there is no telling them otherwise. Mostly they are looking for confirmation, not new evidence to overturn current beliefs. Some believe GMO food and plastics are fine cuz nobody is dropping dead from them. Some believe there is no such thing as safe plastic. I would do my own research, but that's just what I believe.

No, the wort is just as acidic before fermentation as after. Ethanol has a PH very near 7.0 which is neutral.

Nope nope nope nope nope. pH definitely drops significantly throughout the brewing process. Brewing water may have a pH of up to 8 or so, mash pH is in the 5.2-5.6 range, and the pH drops through fermentation to around 3.8-4.4 in finished beer. Anything much above that makes the beer susceptible to microbial infection.

This also has nothing to do with ethanol, which does not ionize, and therefore contributes nothing to the availability of H+ ions (pH) in solution either way.

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I can't be arsed to keep up this list of what's in the fermenters, but hey, check out the cool brewery I own!

Nope nope nope nope nope. pH definitely drops significantly throughout the brewing process. Brewing water may have a pH of up to 8 or so, mash pH is in the 5.2-5.6 range, and the pH drops through fermentation to around 3.8-4.4 in finished beer. Anything much above that makes the beer susceptible to microbial infection.

This also has nothing to do with ethanol, which does not ionize, and therefore contributes nothing to the availability of H+ ions (pH) in solution either way.